US10767022B2 - Fiber wound body, fiber-reinforced resin material, and method for manufacturing fiber wound body - Google Patents

Abstract

This fiber wound body has a plurality of reinforcing fiber yarns wound around a winding axis, each of the reinforcing fiber yarns having a thickness gradient portion in which the fiber content is uniform along the longitudinal direction of the yarn and the thickness gradually changes.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a National Stage of International Application No. PCT/JP2017/022788 filed Jun. 21, 2017, claiming priority based on Japanese Patent Application No. 2016-140681 filed Jul. 15, 2016.

TECHNICAL FIELD

The present invention relates to a fiber wound body used, for example, as a fiber-reinforced base of a load energy absorbing material, a fiber-reinforced resin material in which a fiber wound body is used as a fiber-reinforced base, and a method for manufacturing a fiber wound body.

BACKGROUND ART

A fiber-reinforced resin material is used as a light, strong material. When a fiber-reinforced resin material includes a compound of a fiber-reinforced base and a matrix of, for example, resin, the dynamic properties (mechanical properties) are improved as compared to the matrix itself. The fiber-reinforced base of a fiber-reinforced resin material includes, for example, a fiber wound body manufactured through filament winding (FW) or braiding (braid). The fiber wound body is manufactured by winding a number of reinforced-fiber yarns about a winding axis to have a tubular or solid structure.

A fiber-reinforced resin material is used as, for example, a load energy absorbing material. When the load energy absorbing material is used as, for example, a crash box arranged between a bumper and a frame of a vehicle body, the crash box generally needs to have a required mechanical strength to hold its position. Additionally, when an impact load exceeding the designed value is applied, the crash box needs to deform and collapse while absorbing the impact load.

The strength of the crash box is lowest in the distal portion, which is a portion that first receives an impact load, and gradually increases toward the basal portion. In a crash box of a fiber-reinforced resin material, the cross section of a reinforced fiber yarn may be increased toward the basal portion of the fiber-reinforced base to gradually vary the strength. For example,patent document 1 discloses a tubular fiber body having a transversal cross section, the shape of which changes along its length. The strength is varied by using a thick fiber yarn in a portion having a large diameter and a thin fiber yarn in a portion having a small diameter.

PRIOR ART DOCUMENTPatent Document

Patent Document 1: Japanese National Phase Laid-Open Patent Publication No. 2014-508666

SUMMARY OF THE INVENTIONProblems that are to be Solved by the Invention

There is a demand for reduction in the weight of a fiber-reinforced resin material to reduce the mass of a vehicle that uses the fiber-reinforced resin material. However, in the structure disclosed inpatent document 1, the fiber yarn used in a small diameter portion is obtained by removing a predetermined number of fibers with a removal device, and the fiber yarn used in a large diameter portion, which needs to be strong, is obtained by attaching a predetermined number of fibers with an attachment device. Thus, the mass of fibers in each section is uniform. In other words, the mass of fibers in the fiber-reinforced resin material can be changed in only a stepped manner in accordance with each section. Thus, taking account of the required strength, each section may have a mass of unnecessary fibers. The same problem occurs when a tubular fiber arranged body has a transversal cross section, the shape of which is uniform along its length, and the cross section of a reinforced fiber yarn is increased toward the basal portion of a fiber-reinforced base.

It is an object of the present invention to provide a fiber wound body, a fiber-reinforced resin material, and a method for manufacturing a fiber wound body that achieve weight reduction.

Means for Solving the Problem

To achieve the above object, a fiber wound body includes reinforced fiber yarns wound about a winding axis. Each of the reinforced fiber yarns includes a gradual cross-section change portion. The gradual cross-section change portion has a fiber content rate that is constant in a longitudinal direction of the yarn and has a cross section that gradually changes.

To achieve the above object, a fiber-reinforced resin material includes the fiber wound body described above and a matrix resin. The fiber wound body is a fiber-reinforced base.

To achieve the above object, a method for manufacturing a fiber wound body includes elongating each of reinforced fiber yarns having a cross section constant in a longitudinal direction of the yarn in one direction with a drafting device including roller groups; when elongating the reinforced fiber yarns in one direction, forming a gradual cross-section change portion having a fiber content rate that is constant in the longitudinal direction of the yarn and having a cross section that gradually changes by continuously varying a drafting rate of the drafting device to continuously change the cross section of the reinforced fiber yarns in the one direction; and obtaining a fiber wound body by winding the reinforced fiber yarns including the gradual cross-section change portions about a winding axis.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a first embodiment of a load energy absorbing material.

FIG. 2 is a cross-sectional view of a tubular braid taken along line2-2 inFIG. 1.

FIG. 3 is a cross-sectional view of a tubular braid taken along line3-3 inFIG. 1.

FIG. 4 is a schematic diagram showing a braider.

FIG. 5 is a schematic diagram showing a drafting device.

FIG. 6 is a front view showing a second embodiment of a load energy absorbing material.

FIG. 7 is a cross-sectional view showing a distal portion of a fiber wound body.

FIG. 8 is a cross-sectional view showing a basal portion of a fiber wound body.

FIG. 9 is a schematic diagram of a filament winding device.

FIG. 10 is a front view of a further example of a tubular braid.

FIG. 11 is a front view of a further example of a fiber wound body.

EMBODIMENTS OF THE INVENTIONFirst Embodiment

A first embodiment of a fiber wound body, a fiber-reinforced resin material, and a method for manufacturing a fiber wound body will now be described with reference toFIGS. 1 to 5.

FIG. 1 shows a loadenergy absorbing material10 used as a fiber-reinforced resin material. The loadenergy absorbing material10 includes atubular braid11, which is a fiber wound body used as a fiber-reinforced base, and a matrix resin.

Thetubular braid11 is shaped as a tubular cone in a structure braided by first reinforcedfiber yarns12, second reinforcedfiber yarns13, and third reinforcedfiber yarns14. Thetubular braid11 has an axial end including abasal portion11aand the other axial end including adistal portion11b. In thetubular braid11, a direction in which a winding axis L extends refers to the axial direction.

The first reinforcedfiber yarns12 are arranged parallel to each other. The second reinforcedfiber yarns13 are arranged parallel to each other and intersect with the first reinforcedfiber yarns12. The third reinforcedfiber yarns14 are arranged parallel to each other and intersect with the first reinforcedfiber yarns12 and the second reinforcedfiber yarns13. An angle at which the third reinforcedfiber yarns14 intersect with the first reinforcedfiber yarns12 is equal to an angle at which the third reinforcedfiber yarns14 intersect with the second reinforcedfiber yarns13. The third reinforcedfiber yarns14 are arranged in a generatrix direction of the cone. Thus, thetubular braid11 has a structure in which the first reinforcedfiber yarns12 and the second reinforcedfiber yarns13 are wound around the third reinforcedfiber yarns14. The first reinforcedfiber yarns12 and the second reinforcedfiber yarns13 are wound about the winding axis L.

The first reinforcedfiber yarns12 and the second reinforcedfiber yarns13 are configured to be oblique yarn lines in thetubular braid11. The third reinforcedfiber yarns14 are configured to be axial yarn lines in thetubular braid11. The first reinforcedfiber yarns12 are arranged to intersect with the winding axis L of thetubular braid11 at an oblique angle θ. The second reinforcedfiber yarns13 are arranged to intersect with the winding axis L of thetubular braid11 at an angle −θ, which is opposite to the oblique angle θ. The oblique angle θ is set in accordance with, for example, the shape of thetubular braid11 and the required strength.

The first to third reinforcedfiber yarns12 to14 are formed by spinning non-continuous fibers. The first to third reinforcedfiber yarns12 to14 are formed of carbon fibers, but may be formed of glass fibers or resin fibers. The first to third reinforcedfiber yarns12 to14 include gradualcross-section change portions20, each of which has a cross section that continuously decreases from thebasal portion11atoward thedistal portion11bof thetubular braid11. In the present embodiment, the cross section of the reinforcedfiber yarns12 to14 (gradual cross-section change portions20) refers to the lateral dimension and the transverse dimension of a low-profile cross section of the reinforcedfiber yarns12 to14. That is, continuous change in the cross section of a gradualcross-section change portion20 refers to continuous change in both the lateral dimension and the transverse dimension of the gradualcross-section change portion20. Alternatively, one of the lateral dimension and the transverse dimension of the gradualcross-section change portion20 may be fixed while the other dimension continuously changes.

As shown inFIGS. 2 and 3, thetubular braid11 includes a gradualthickness change portion18. When the dimension of thetubular braid11 in the radial direction refers to the thickness, the thickness of the gradualthickness change portion18 increases toward thebasal portion11a. That is, the thickness of the gradualthickness change portion18 decreases toward thedistal portion11b. Thus, the thickness of thetubular braid11 gradually decreases from thebasal portion11atoward thedistal portion11balong the winding axis L. Each of the reinforcedfiber yarns12 to14 has a fiber content rate that is the same at any position in a longitudinal direction of the yarn. Accordingly, thetubular braid11 has a fiber content rate that is the same at any position in the axial direction. The fiber content rate of each of the reinforcedfiber yarns12 to14 refers to the proportion of fibers occupied in the total cross-sectional area of the respective the reinforcedfiber yarns12 to14.

Thetubular braid11 having the configuration described above is manufactured using a braider (braiding device) including a drafting device.

As shown inFIG. 4, abraider30 includes firstoblique yarn feeders32aand secondoblique yarn feeders32b. The first reinforcedfiber yarns12 are fed out of the firstoblique yarn feeders32ato a circumferential surface of amandrel31 at a predetermined angle with respect to the axis of themandrel31. The second reinforcedfiber yarns13 are fed out of the secondoblique yarn feeders32bto the circumferential surface of themandrel31 at a predetermined angle with respect to the axis of themandrel31. The first reinforcedfiber yarns12 fed out of the firstoblique yarn feeders32aare provided to themandrel31 at an angle +θ. The second reinforcedfiber yarns13 fed out of the secondoblique yarn feeders32bare provided to themandrel31 at an angle −θ. In the present embodiment, the predetermined angle is 45°. Theoblique yarn feeders32aand32bfeed out the reinforcedfiber yarns12 and13 that do not include the gradualcross-section change portions20 and thus have a constant cross section.

Thebraider30 includesaxial yarn feeders33. The third reinforcedfiber yarns14 are fed out of theaxial yarn feeders33 and arranged in the axial direction of themandrel31. Theaxial yarn feeders33 feed out the third reinforcedfiber yarns14 that do not have the gradualcross-section change portions20 and thus have a constant cross section.

Thebraider30 includes draftingdevices40. Thedrafting devices40 are arranged at a downstream side of thefeeders32a,32b, and33 in a direction in which theoblique yarn feeders32aand32band theaxial yarn feeders33 feed the reinforcedfiber yarns12 to14. Thedrafting devices40 respectively receive the reinforcedfiber yarns12 to14 from thefeeders32a,32b, and33 and elongate the reinforcedfiber yarns12 to14.

As shown inFIG. 5, each of thedrafting devices40 includes afront roller group42 and aback roller group43. Thefront roller group42 includesrollers42a. Theback roller group43 includesrollers43a. When the reinforcedfiber yarns12 to14 are fed out of theoblique yarn feeders32aand32band theaxial yarn feeders33 to themandrel31, while the circumferential speed of theback roller group43 is kept constant, the circumferential speed of thefront roller group42 is continuously increased. Consequently, the cross section of the reinforcedfiber yarns12 to14 that have passed through thefront roller group42 gradually decreases from the cross section at a point in time when the reinforcedfiber yarns12 to14 passed through theback roller group43.

The reinforcedfiber yarns12 to14 are elongated so that the cross section of the reinforcedfiber yarns12 to14 gradually decreases toward the downstream side in the feeding direction. As a result, each of the reinforcedfiber yarns12 to14 has a cross section that gradually decreases and includes the gradualcross-section change portion20. Additionally, the drafting rate is lower toward the upstream side in the feeding direction. Thus, the cross section of the reinforcedfiber yarns12 to14 remains close to the cross section of the reinforcedfiber yarns12 to14 that have not been elongated.

When the reinforcedfiber yarns12 to14 are fed out of thedrafting devices40 to themandrel31, thetubular braid11 is obtained. The obtainedtubular braid11 is impregnated with a thermosetting resin and cured to manufacture the loadenergy absorbing material10. The impregnation and curing of the resin is performed through resin transfer molding (RTM) but may be performed through a process other than resin transfer molding (RTM).

As shown inFIG. 1, in the loadenergy absorbing material10 in which thetubular braid11 is used as the fiber-reinforced base, as described above, the thickness of thetubular braid11 gradually increases from thedistal portion11btoward thebasal portion11ain the axial direction because of the gradualthickness change portion18. The strength of the loadenergy absorbing material10 is lowest in the distal portion, which corresponds to thedistal portion11bof thetubular braid11. The strength of the loadenergy absorbing material10 gradually increases from thedistal portion11btoward thebasal portion11ain the axial direction of thetubular braid11.

The embodiment has the operation and advantages described below.

(1) In thetubular braid11 of the loadenergy absorbing material10, the first to third reinforcedfiber yarns12 to14 include the gradualcross-section change portions20. The gradualcross-section change portions20 gradually change the cross section of the first to third reinforcedfiber yarns12 to14 so that the strength of thetubular braid11 gradually varies along the winding axis L. Thetubular braid11 includes the gradualthickness change portion18, the thickness of which gradually changes in accordance with the gradualcross-section change portions20. The thickness of the gradualthickness change portion18 of thetubular braid11 gradually changes in accordance with changes in the cross section of the first to third reinforcedfiber yarns12 to14. This allows the gradualthickness change portion18 to have the same fiber content rate at any position in the axial direction of thetubular braid11. Thus, even when the thickness of thetubular braid11 is changed, the weight reduction may be achieved as compared to, for example, when further reinforced fibers are added to the first to third reinforcedfiber yarns12 to14 to increase the thickness or reinforced fibers are removed from the first to third reinforcedfiber yarns12 to14 to decrease the thickness so that the strength of thetubular braid11 varies.

(2) For example, when first to third reinforced fiber yarns have a uniform cross section and are used to manufacture a tubular braid, the oblique angle θ of the first and second reinforced fiber yarns needs to be controlled to vary the strength in the axial direction of the tubular braid. Such control is complex. Additionally, the design of the oblique angle θ will be complex to achieve the weight reduction. In this regard, in thetubular braid11 of the embodiment, the thickness is smoothly and gradually changed in accordance with the gradualcross-section change portions20. More specifically, the cross section of the first to third reinforcedfiber yarns12 to14 is increased on a thick portion of thetubular braid11, and the cross section of the first to third reinforcedfiber yarns12 to14 is decreased on a thin portion of thetubular braid11. This allows the strength of thetubular braid11 to vary in the axial direction without changing the oblique angle θ of the first and second reinforcedfiber yarns12 and13. Thetubular braid11 is manufactured without a complex control of the oblique angle θ.

(3) The cross section of the gradualcross-section change portions20 of the first to third reinforcedfiber yarns12 to14 is smoothly changed and is not abruptly changed such as in a stepped manner. Accordingly, the thickness of thetubular braid11 is smoothly changed, and the strength is smoothly changed.

(4) In thetubular braid11, the oblique angle θ of the first and second reinforcedfiber yarns12 and13 is constant from thebasal portion11ato thedistal portion11b. For example, when thetubular braid11 is manufactured so that first to third reinforced fiber yarns have a uniform cross section and have a constant oblique angle at the distal portion and the basal portion of the tubular braid, the length of the first and second reinforced fiber yarns extending around the tubular braid once increases at positions toward the basal portion of the tubular braid where the diameter increases. This increases a gap between adjacent ones of the first reinforced fiber yarns and a gap between adjacent ones of the second reinforced fiber yarns. Consequently, the strength of the load energy absorbing material is lowered toward the basal portion of the tubular braid. In this case, to maintain the strength of the basal portion, the oblique angle of the first reinforced fiber yarns and the second reinforced fiber yarns needs to be gradually changed toward the basal portion so that the gap of adjacent ones of the first reinforced fiber yarns and the gap of adjacent ones of the second reinforced fiber yarns are maintained. In this regard, the first and second reinforcedfiber yarns12 and13 include the gradualcross-section change portions20. The gap between adjacent ones of the first reinforcedfiber yarns12 and the gap between adjacent ones of the second reinforcedfiber yarns13 will not be excessively increased even at thebasal portion11ahaving a large diameter, and the strength will not be lowered. This eliminates the need for a change in the oblique angle of the first and second reinforcedfiber yarns12 and13 and allows thetubular braid11 to be easily manufactured without lowering the strength.

(5) In thetubular braid11, each of the first to third reinforcedfiber yarns12 to14 includes the gradualcross-section change portion20. The strength is easily adjusted at any position in the axial direction of thetubular braid11 by controlling the cross section of each of the first to third reinforcedfiber yarns12 to14.

(6) Thebraider30 manufacturing thetubular braid11 includes thedrafting devices40 at the downstream side of theoblique yarn feeders32aand32band theaxial yarn feeders33 in the feeding direction. The cross section is gradually changed with thedrafting devices40 by controlling the drafting rate of each of the reinforcedfiber yarns12 to14 fed out of theoblique yarn feeders32aand32band theaxial yarn feeders33. When the drafting rate is controlled by thedrafting devices40, thetubular braid11 having a target thickness is manufactured.

Second Embodiment

A second embodiment of a fiber wound body, a fiber-reinforced resin material, and a method for manufacturing a fiber wound body will now be described with reference toFIGS. 6 to 9. In the second embodiment, the same reference characters are given to those elements that are the same as the corresponding elements of the first embodiment. Such elements will not be described in detail.

As shown inFIG. 6, a second embodiment of a loadenergy absorbing material70 used as a fiber-reinforced resin material includes afiber wound body51, which is used as the fiber-reinforced base, and a matrix resin.

The fiber woundbody51 is tubular. The fiber woundbody51 has a structure in which afirst fiber layer54, which is an inner layer formed by a first reinforcedfiber yarn52, and asecond fiber layer55, which is an outer layer formed by a second reinforcedfiber yarn53 at a radially outer side of thefirst fiber layer54, are stacked on each other. In the fiber woundbody51, a direction in which the winding axis L extends refers to the axial direction. The fiber woundbody51 has an axial end including abasal portion51aand the other axial end including adistal portion51b.

The first reinforcedfiber yarn52 is wound to intersect with the winding axis L of the fiber woundbody51 at an angle ±θ. The second reinforcedfiber yarn53 is wound to intersect with the winding axis L of the fiber woundbody51 at the angle ±θ. The intersecting angle θ of each of the reinforcedfiber yarns52 and53 is set in accordance with, for example, the shape of the fiber woundbody51 and the required strength.

The first and second reinforcedfiber yarns52 and53 are obtained by spinning non-continuous fibers. The first and second reinforcedfiber yarns52 and53 are formed by carbon fibers but may be formed of glass fibers or resin fibers. The first reinforcedfiber yarn52 and the second reinforcedfiber yarn53 each include a gradualcross-section change portion56 having a cross section that continuously decreases from thebasal portion51atoward thedistal portion51bof the fiber woundbody51.

As shown inFIGS. 7 and 8, the fiber woundbody51 includes a gradualthickness change portion57. The thickness of the gradualthickness change portion57 increases toward thebasal portion51aand decreases toward thedistal portion51b. Thus, the thickness of the fiber woundbody51 is gradually decreased by the gradualthickness change portion57 from thebasal portion51atoward thedistal portion51balong the winding axis L. The cross section of the gradualcross-section change portion56 regularly decreases from a thick part toward a thin part of the gradualthickness change portion57. Even when the thickness of the fiber woundbody51 is changed, the gradualthickness change portion57 is formed by the gradualcross-section change portions56 of the reinforcedfiber yarns52 and53. Thus, each of the reinforcedfiber yarns52 and53 has a fiber content rate that is the same at any position in a longitudinal direction of the yarn. Accordingly, the fiber woundbody51 has a fiber content rate that is the same at any position in the axial direction.

The fiber woundbody51 is tapered so that the outer diameter gradually decreases from thebasal portion51atoward thedistal portion51b. The inner diameter of the fiber woundbody51 is constant from thebasal portion51atoward thedistal portion51b.

The fiber woundbody51 is manufactured through filament winding. As shown inFIG. 9, afilament winding device60 manufacturing the fiber woundbody51 includes amandrel61, a feedinghead62, aresin bath63, adrafting device64, and abobbin65. In the same manner as the first embodiment, the draftingdevice64 includes a front roller and a back roller. The reinforcedfiber yarns52 and53 that do not include the gradualcross-section change portion56 and thus have a constant cross section are wound around thebobbin65.

When fed out of thebobbin65, the reinforcedfiber yarns52 and53 are elongated by the draftingdevice64. As the reinforcedfiber yarns52 and53 move from thebobbin65 toward the downstream side in the feeding direction, the reinforcedfiber yarns52 and53 are elongated so that the cross section gradually decreases. When the cross section of each of the reinforcedfiber yarns52 and53 is gradually decreased, the gradualcross-section change portion56 is manufactured.

The reinforcedfiber yarns52 and53 including the gradualcross-section change portions56 are impregnated with a resin in theresin bath63 and then directed to the feedinghead62. The reinforcedfiber yarns52 and53 impregnated with the resin in theresin bath63 are wound around amandrel61 via the feedinghead62. At this time, angles at which the reinforcedfiber yarns52 and53 are wound around themandrel61 are adjusted.

The beginning of winding in the fiber woundbody51 corresponds to thebasal portion51a. As the reinforcedfiber yarns52 and53 are elongated by the draftingdevice64 so that the cross section gradually decreases, the reinforcedfiber yarns52 and53 are wound around themandrel61. When the winding is completed, the gradualcross-section change portion56 is manufactured. The drafting rate of the reinforcedfiber yarns52 and53 is lower toward the beginning of winding. Thus, the cross section of the reinforcedfiber yarns52 and53 is closer to the cross section of the reinforcedfiber yarns52 and53 that have not been elongated at positions toward the beginning of winding.

As shown inFIG. 6, in the loadenergy absorbing material70 in which the fiber woundbody51 is used as the fiber-reinforced base, as described above, the thickness of the fiber woundbody51 gradually increases from thedistal portion51btoward thebasal portion51ain the axial direction because of the gradualthickness change portion57. Thus, the strength of the loadenergy absorbing material70 is lowest in a distal portion corresponding to thedistal portion51bof the fiber woundbody51. The strength of the loadenergy absorbing material70 gradually increases from thedistal portion51btoward thebasal portion51ain the axial direction of the fiber woundbody51.

The second embodiment has the advantages described below in addition to the advantages of the first embodiment.

(7) In the fiber woundbody51 of the loadenergy absorbing material70, the first and second reinforcedfiber yarns52 and53 include the gradualcross-section change portions56. The fiber woundbody51 includes the gradualthickness change portion57, the thickness of which gradually changes in accordance with the gradualcross-section change portions56. The thickness of the gradualthickness change portion57 of the fiber woundbody51 gradually changes in accordance with changes in the cross section of the first and second reinforcedfiber yarns52 and53. This allows the fiber content rate to be the same at any position in the axial direction of the fiber woundbody51. Thus, even when the thickness of the fiber woundbody51 is changed to vary the strength of the fiber woundbody51, weight reduction may be achieved.

(8) The fiber woundbody51 is manufactured through filament winding. For example, when a yarn having a uniform cross section is used in filament winding to manufacture a fiber wound body, a fiber layer for reinforcement needs to be added to a portion that needs higher strength to vary the strength of the fiber woundbody51 in the axial direction. In this case, the weight will be increased by an amount corresponding to the added fiber layer for reinforcement. In this regard, the cross section of each of the reinforcedfiber yarns52 and53 is increased toward thebasal portion51aof the fiber woundbody51. This increases the strength of thebasal portion51aand eliminates the need for reinforcement of thebasal portion51a. Thus, the loadenergy absorbing material70 is easily manufactured without increasing the weight.

(9) In the fiber woundbody51, two kinds of the reinforcedfiber yarns52 and53 each include the gradualcross-section change portion56. Thus, the strength of the fiber woundbody51 is easily adjusted at any position in the axial direction by controlling the cross section of the first and second reinforcedfiber yarns52 and53.

(10) Thefilament winding device60 manufacturing the fiber woundbody51 includes thedrafting device64 at the downstream side of the feedinghead62 in the feeding direction. The cross section of each of the reinforcedfiber yarns52 and53 fed out of the feedinghead62 is gradually changed with the draftingdevice64. The fiber woundbody51 may be manufactured while changing the cross section of each of the reinforcedfiber yarns52 and53. Additionally, before the reinforcedfiber yarns52 and53 are impregnated in theresin bath63, the reinforcedfiber yarns52 and53 are elongated by the draftingdevice64. Thus, the reinforcedfiber yarns52 and53 are smoothly elongated.

The present embodiment may be modified as follows.

As shown inFIG. 10, thetubular braid11 may be tubular and have a constant diameter in the axial direction.

As shown inFIG. 11, the fiber woundbody51 may be shaped as a tubular cone.

In thetubular braid11 of the first embodiment, the first reinforcedfiber yarns12 and the second reinforcedfiber yarns13, or the oblique yarn lines, do not need to include the gradualcross-section change portions20. More specifically, in thetubular braid11, only the third reinforcedfiber yarns14, or the axial yarn lines, may include the gradualcross-section change portions20. Alternatively, when at least one of the first reinforcedfiber yarns12 and the second reinforcedfiber yarns13, or the oblique yarn lines, includes the gradualcross-section change portions20, and the third reinforcedfiber yarns14, or the axial yarn lines, do not have to include the gradualcross-section change portions20. More specifically, reinforced fiber yarns including the gradualcross-section change portions20 may be selected from the first to third reinforcedfiber yarns12 to14 to control the thickness of thetubular braid11.

In the second embodiment, the number of stacked fiber layers may be three or more.

The fiber-reinforced resin material using thetubular braid11 and the fiber woundbody51 may be used as a structural material instead of a load energy absorbing material. Additionally, thetubular braid11 and the fiber woundbody51 may be used in a fiber-reinforced compound including a matrix material other than a matrix resin.

In thedrafting devices40 and64, the number of roller groups may be changed.

The fiber wound body may be manufactured in a solid structure, instead of a tubular structure, using a three-dimensional braider (three-dimensional braiding device).

The thickness of thetubular braid11 or the fiber woundbody51 may be constant from thebasal portions11aand51atoward thedistal portions11band51b.

Claims (5)

The invention claimed is:

1. A fiber wound body comprising:

reinforced fiber yarns wound about a winding axis, wherein

each of the reinforced fiber yarns includes a gradual cross-section change portion, and

the gradual cross-section change portion has a fiber content rate that is constant in a longitudinal direction of the yarn and has a cross section that gradually changes.

2. The fiber wound body according toclaim 1, further comprising a gradual thickness change portion having a thickness that gradually changes along the winding axis, wherein

the thickness is a dimension of the fiber wound body in a radial direction,

the gradual thickness change portion has a thick part and a thin part, and

the cross section of the gradual cross-section change portion regularly decreases from the thick part toward the thin part of the gradual thickness change portion.

3. The fiber wound body according toclaim 1, wherein

the reinforced fiber yarns include first reinforced fiber yarns, second reinforced fiber yarns, and third reinforced fiber yarns,

the fiber wound body includes a braid,

the first reinforced fiber yarns are arranged parallel to each other,

the second reinforced fiber yarns are arranged parallel to each other and intersect with the first reinforced fiber yarns,

the third reinforced fiber yarns are arranged parallel to each other and intersect with the first and second reinforced fiber yarns, and

an angle at which the third reinforced fiber yarns intersect with the first reinforced fiber yarns is equal to an angle at which the third reinforced fiber yarns intersect with the second reinforced fiber yarns.

4. A fiber-reinforced resin material, comprising:

the fiber wound body according toclaim 1, the fiber wound body being a fiber-reinforced base; and

a matrix resin.

5. A method for manufacturing a fiber wound body, the method comprising:

elongating each of reinforced fiber yarns having a cross section constant in a longitudinal direction of the yarn in one direction with a drafting device including roller groups;

when elongating the reinforced fiber yarns in one direction, forming a gradual cross-section change portion having a fiber content rate that is constant in the longitudinal direction of the yarn and having a cross section that gradually changes by continuously varying a drafting rate of the drafting device to continuously change the cross section of the reinforced fiber yarns in the one direction; and

obtaining a fiber wound body by winding the reinforced fiber yarns including the gradual cross-section change portions about a winding axis.

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